The invention relates to radiofrequency networks in which the network units communicate with one another by means of radiofrequency links and, more particularly, a method, in the networks, which permits two units in the network to recognise each other and to then communicate in a secure manner.
Making radiofrequency links between electronic units such as a personal computer, a printer, a mobile or fixed-line phone, etc., is known by making use of, for example, the specifications of a network known as “BLUETOOTH” which are defined in documents ETS 300-328 and ETS 300-339.
In such a BLUETOOTH network, the units each have an address by which they can be identified but this address is clearly transmitted in radiofrequency signals. The result is that the radiofrequency links are not secure.
To overcome this problem, it is proposed to enter an identical secret code in each of the two units to be connected and this will then permit session keys to be generated for authentication and encryption.
This process can prove to be tiresome, in that it is necessary to key in the code twice on a keyboard and the code may have numerous digits or letters.
Moreover, some network units, an earphone for a mobile phone, for example, might not have a keyboard, with the result that this code must be registered permanently, or almost permanently, in the unit with no keyboard. This leads to permission to access the network for anyone who picks up the unit, without having to identify themselves as a user.
It is also proposed to connect the two units with a cable link in order to exchange the session keys under maximum security, to ensure subsequent authentication and encryption. The inconvenient thing about this solution resides in the fact that each unit must be fitted with a special plug which will differ from one unit to another. An aim of the present invention, therefore, is to implement a process of recognition between two units in a radiofrequency network, a method which allows secure recognition of the two units to occur.